As is known there exist various instruments for the settlement of commercial exchanges or the transfer of goods and services between one individual and another. In addition to legal tender, used in general for negotiations of small amount, there are used credit documents, e.g. bank and bankers checks, whose function is to limit the risks connected with circulation of said credits. Another instrument used widely and which allows making payments consists of credit cards consisting of non-transferable documents which authorize the holder to purchase goods and services from third parties approved by the issuer of the card, in general banks and financial organizations, to which is transferred the onus of payment.
The payment instruments alternative to cash avoid the user's holding available an amount of money, sometimes large, with the related risks. Even these instruments are not considered quite safe. Credit cards can be readily used by third parties at least up to the time of reporting of their robbery or loss, while checks, despite numerous provisions adopted, can be skillfully counterfeited and falsified. Given the large number of payment operations performed each day it is understandable that these problems are perceived in a very serious manner, considering that they involve simultaneously numerous individuals, i.e. the customers, credit organizations, and the authorities responsible for control and repression.